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Proceedings Paper

Robust magnetic-field-free skyrmions above room temperature in a bulk chiral magnet (Conference Presentation)
Author(s): Kosuke Karube; Jonathan S. White; Marek Bartkowiak; Daisuke Morikawa; Xiuzhen Yu; Akiko Kikkawa; Yusuke Tokunaga; Takahisa Arima; Henrik M. Rønnow; Yoshinori Tokura; Yasujiro Taguchi

Paper Abstract

Magnetic skyrmions, vortex-like topological spin textures, have attracted much attention in terms of both fundamental physics and spintronics applications. Thus far, skyrmions have been observed in thin-film multilayers with interfacial Dzyaloshinskii-Moriya interaction (DMI) and structurally-chiral magnets with bulk DMI. Recently, bulk-DMI-induced skyrmions have been observed above room temperature in Co-Zn-Mn alloys with a β-Mn-type chiral structure [1]. In most chiral magnets, however, skyrmions exist as a thermodynamically equilibrium state only in a narrow temperature and magnetic field region just below the magnetic transition temperature Tc. The limited region of the stable skyrmions is unfavorable for applications. Here, we focused on β-Mn-type Co9Zn9Mn2 (Tc ~ 400 K) and performed small-angle neutron scattering, magnetic susceptibility and Lorentz transmission electron microscope measurements. We demonstrated that skyrmions persist over almost the whole temperature region below 400 K as a long-lived metastable state by performing a conventional field-cooling process. Once created, metastable skyrmions survive above room temperature after removal of magnetic field [2]. These findings exemplify the topological robustness of the once-created skyrmions and provide a significant step toward applications of skyrmions in bulk chiral magnets. In the presentation, we will discuss the details of the above observations, and also show novel skyrmion states in Co-Zn-Mn alloys with other chemical compositions. [1] Y. Tokunaga et al., Nat. Commun. 6, 7638 (2015). [2] K. Karube et al., Phys. Rev. Mater. 1, 074405 (2017).

Paper Details

Date Published: 18 September 2018
Proc. SPIE 10732, Spintronics XI, 107323H (18 September 2018); doi: 10.1117/12.2319900
Show Author Affiliations
Kosuke Karube, RIKEN (Japan)
Jonathan S. White, Paul Scherrer Institut (Switzerland)
Marek Bartkowiak, Paul Scherrer Institut (Switzerland)
Daisuke Morikawa, RIKEN (Japan)
Xiuzhen Yu, RIKEN (Japan)
Akiko Kikkawa, RIKEN (Japan)
Yusuke Tokunaga, The Univ. of Tokyo (Japan)
Takahisa Arima, RIKEN (Japan)
Henrik M. Rønnow, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Yoshinori Tokura, RIKEN (Japan)
Yasujiro Taguchi, RIKEN (Japan)

Published in SPIE Proceedings Vol. 10732:
Spintronics XI
Henri-Jean Drouhin; Jean-Eric Wegrowe; Manijeh Razeghi; Henri Jaffrès, Editor(s)

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